Liquid chromatography is a form of chromatography used frequently in biochemistry and analytical chemistry to separate, identify, and quantify compounds based on their properties such as polarity and their interactions with a stationary phase. Liquid chromatography can be performed using planar or column techniques. In both cases, the system includes a chromatographic device with a stationary phase, a means for moving a mobile phase (solvent carrying compounds of interest) through the device (such as a pump, or gravity), and a detector that creates an electrical signal that identifies a particular compound based on the time of the signal and the amount of the compound based on the intensity of the signal. The detector may also provide other characteristic information (e.g. UV/Vis spectroscopic data for a compound if so equipped). Retention time of a compound in the device varies depending on the strength of the compound's interactions with the stationary and mobile phases, the ratio/composition of the mobile phase that is used, and the flow rate of the mobile phase.
The composition of the mobile phase flowing through the chromatographic device is critical to obtaining the required separation of compounds. For example, in ion exchange chromatography, the pH and/or salt concentration of the mobile phase changes over the course of the separation, to elute different compounds at different times. Prior art systems allowed users to blend multiple solvents to create mobile phases of particular pH and/or salt concentrations. However, in these systems the user was required to know not only the pH and salt concentrations of their particular solvents, but also the pH and salt concentrations that would result from mixing the solvents in various proportions. It would be desirable to have a system and method for automatically calculating and blending the solvents in the desired proportions, to produce a particular pH and/or salt concentration specified by a user, and for varying the proportions of solvents over the course of the elution.